Equations · equation
No-Cloning Theorem
Quantum Computing · 1982
- Equation
- no U exists with U(|ψ⟩|0⟩) = |ψ⟩|ψ⟩
- Field
- Quantum Computing
- Named After
- William Wootters · Wojciech Zurek · Dennis Dieks
- Symbols
- |ψ⟩ an arbitrary unknown quantum state · U any allowed (unitary) operation · the theorem: no universal copier is possible
- Year
- 1982
Significance
Unknown quantum states cannot be photocopied — linearity forbids it. The apparent handicap is a feature: an eavesdropper can't copy a quantum key without leaving fingerprints, which makes quantum cryptography possible, and it's why quantum error correction had to be invented rather than borrowed.
Referenced by
element
equation
theory
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